when I came to Germany I met Muslims who told me that if the meat (Chicken or beef or lamb) is not slaughtered by a Muslim or using the Islamic way, it is haram to eat it. I always thought when I eat any meats {non-pork }, if I say Bismillah before eating it, it is halal all the time I buy meats from the stores and had no idea that it is haram. Meat slaughtered by Muslims is available at a driving distance and always more expensive, but I can afford it.
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
It is forbidden for the Muslim to eat the meat of an animal that is not slaughtered according to Islamic rites as Allah Says (what means) {Prohibited to you are dead animals, blood, the flesh of swine, and that which has been dedicated to other than Allah, and [those animals] killed by strangling or by a violent blow or by a head-long fall or by the goring of horns, and those from which a wild animal has eaten, except what you [are able to] slaughter [before its death], and those which are sacrificed on stone altars, and [prohibited is] that you seek decision through divining arrows. That is grave disobedience.} [Quran 5:3]
Besides, the Prophet said: “When an animal is slaughtered (according to Islamic rites) and the name of Allah is mentioned on it, then eat from its meat.” [Al-Bukhari]
It is a condition that the slaughterer be a Muslim or somebody from the people of the Book (Christian or Jew) as Allah Says (what means) {This day [all] good foods have been made lawful, and the food of those who were given the Scripture is lawful for you and your food is lawful for them.} [Quran 5:5]
As for the pagan, the idolater, the atheist or the communist, the meat of animals slaughtered by them is unlawful for Muslims.
Saying Bismillah (in the Name of Allah) does not make the meat lawful to Muslims if it is not from an animal slaughtered by Muslims, Jews or Christians.
It is true that Al-Bukhari reported the following from ‘Aa’ishah that she said: “O Prophet of Allah! Meat is brought to us by some people and we are not sure whether the name of Allah has been mentioned on it or not (at the time of slaughtering the animals).” The Prophet of Allah said (to them), “Mention the name of Allah and eat it.” But this is not an evidence that saying Bismillah on some meat that is not slaughtered legally according to Islamic rites, makes that meat lawful for us. The issue in the Hadeeth is about whether those Muslims who slaughtered the animal (according to Islamic rites) said Bismillah or not.
So, the Prophet told ‘Aa’ishah and indeed the address is to all Muslims to say Bismillah and eat from that meat on which Bismillah might not have been said when slaughtering.
Allah knows best.
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